1. Field of the Invention
This invention pertains generally to low head loss flow control valves. More particularly, the invention pertains to fixed cone sleeve valves having ribs downstream of the gate for supporting the cone, velocity diffusers, and velocity shredders.
2. General Background
Sleeve valves have been employed to control the flow rate and head pressure of fluids in industrial piping systems, hydro power facilities, agricultural facilities, water and sewage distribution systems, and industrial piping systems. Sleeve valves are often utilized for their ability to operate without the moving components of the valve having to work against the head pressure of the fluid being supplied to the valve. An example of a fixed cone sleeve valve is described in U.S. Pat. No. 6,296,009, entitled Arm-Driven Sleeve Valve With Centralized Drive Mechanism, which issued Oct. 2, 2001 and is hereby incorporated in its entirety by reference. Conventional arm-driven sleeve valves often comprise a tubular inlet conduit, a tubular gate, and a cone shaped shut-off member. It is common for the shut-off member to be rigidly attached to the inlet conduit via a plurality of ribs that extend into the fluid passageway of the inlet conduit. Other sleeve valves, such as is disclosed in U.S. Pat. No. 1,477,722, entitled Valve, which issued Dec. 18, 1923, and is hereby incorporated in its entirety by reference, comprise ribs downstream of the inlet conduit for supporting the shut-off member. The gate typically is linearly movable over the inlet conduit in a telescoping manner and in a manner such that it is able to engage against the shut-off member to prevent fluid from passing through the valve.
Although such fixed cone sleeve valves have proven to be highly useful, there are also problems related to such valves. One such problem with valves in which the shut-off member is rigidly attached to the inlet conduit via a plurality of ribs that extend into the fluid passageway of the inlet conduit is that the ribs that secure the shut-off member to the inlet conduit obstruct the fluid passageway within the inlet conduit, and thereby slightly restrict the flow through the valve. As can be appreciated, this lowers the overall efficiency of the valve. Even in sleeve valves in which the ribs downstream of the inlet conduit support the shut-off member, the flow downstream of the inlet conduit is non-linear and can cause non-uniform pressure differentials that can cold work or work harden the housing and ribs of such valves. Cold working the housing and ribs can cause the housing and ribs to become brittle and fracture due to fatigue. Moreover, velocity differentials of the fluid flow downstream of the inlet conduit can cause significant drag on the fluid as it passes through a sleeve valve.